Spatial and temporal variability in concentration and characteristics of aerosols at Visakhapatnam (east) and Goa (west) coasts of India
2020
Yadav, K. | Sarma, V. V. S. S. | Dileep Kumar, M.
Knowledge on the variability in quantity and compositions of various size groups of aerosols is important to understand their sources and their role in biogeochemical and climate processes. Here, we studied total suspended particles (TSP), PM₁₀ and PM₂.₅ for their quantitative and water soluble compositional (F⁻, Cl⁻, SO₄²⁻, NO₃⁻, NH₄⁺, Na⁺, K⁺, Ca²⁺, and Mg²⁺) distributions, and to understand their nature and potential sources at Goa and Visakhapatnam on the west and east coasts, respectively, of India. While the mean concentrations of TSP were found to be 117 ± 44 and 85 ± 51 μg/m³ its maximal levels occurred in spring intermonsoon (SIM; 141 ± 52) and winter monsoon (WM; 155 ± 145 μg/m³) seasons at Goa and Visakhapatnam, respectively. PM₁₀ and PM₂.₅ exhibited higher ranges at Visakhapatnam than Goa. The increase in PM₂.₅ abundance from WM to SIM at Visakhapatnam seems to occur in coincidence with decrease in TSP favored by topography and ambient meteorological conditions. Locally released and seasonally transported (from land and sea) constituents contributed to the observed variability in aerosol compositions. Sulphate dominated the aerosol composition at both Goa (57–64%) and Visakhapatnam (43–55%) followed by NO₃⁻ (5–16% and 6–18%, respectively) where the former component was higher in PM₁₀ and PM₂.₅. The NO₃⁻ was more in TSP. Relations between SO₄²⁻ and NH₄⁺ suggested possible presence of NH₄HSO₄. Examination of ionic ratios and balance suggested near neutrality in PM₁₀ and PM₂.₅ while TSP was acidic at the both locations. Notable relations between Ca²⁺ and NO₃⁻, particularly in PM₁₀ at Goa, indicated their release from mining related activities.
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